Sierra MP39100 Marine Ignition Starter Switch – 3-Position, Magneto, 5-Screw, 12V/15A
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Sierra MP39100 Marine Ignition Starter Switch – 3-Position Magneto, 5-Screw Terminal, 12V/15A
The Sierra MP39100 is a heavy-duty marine ignition starter switch built for magneto ignition systems in the standard 1-1/8" cylinder format. A corrosion-resistant polyester housing with an inner cylinder seal keeps moisture out and prevents shorts — making it a dependable long-term choice for saltwater and high-humidity marine environments. The 3-position action — Off, Ignition, and Start — delivers clean, positive control over engine startup and shutdown, backed by a 30A solenoid rating and a 15A circuit rating.
The 5-screw terminal layout accommodates standard magneto ignition wiring configurations. The 1-1/8" cylinder diameter and 7/8" mounting hole fit a wide range of marine dash panels. Note: this switch does not include a push-to-choke function or a boot.
Key Specifications
- Part Number: 11-MP39100
- Switch Type: 3-Position (Off – Ignition – Start)
- Ignition Type: Magneto
- Voltage: 12V DC
- Current Rating: 15A
- Solenoid: 30A
- Cylinder Diameter: 1-1/8"
- Mounting Hole: 7/8"
- Terminals: 5 Screw
- Housing Material: Polyester (corrosion-resistant)
- Inner Cylinder Seal: Yes
- Push-to-Choke: Not included
- Boot: Not included
Compatible Applications
- Outboard and inboard engines with magneto ignition systems using standard 5-terminal wiring
- Marine helm panels with a 7/8" mounting hole accepting a 1-1/8" cylinder switch
- 12V DC electrical systems requiring a 3-position Off/Ignition/Start switch
- Direct replacement for worn or damaged OEM 5-screw magneto ignition switches
Parts Desk Insights
The MP39100 is the go-to magneto ignition switch when your engine uses a standard 5-terminal wiring harness and you need the larger 1-1/8" cylinder format — the most common configuration for mid-size and larger outboards with magneto ignition. No push-to-choke is included, so if your engine requires choke control through the switch, the Sierra MP39760 Magneto Switch (compact 5/8" cylinder, includes push-to-choke) is the better fit. If your magneto wiring harness requires 6 terminals rather than 5, step up to the Sierra MP39090 Magneto 6-Screw Switch. For a brass-bodied magneto switch, the Sierra MP39040 Brass Magneto Switch is available at 10A. If your engine runs a conventional ignition rather than magneto, the Sierra MP39770 Conventional Polyester Switch is the correct fit.
Shipping information
In-stock and OEM parts: ship same or next business day.
Locally warehoused items: ship within 1-3 business days.
Special-order items: timeline confirmed after order.
Returns & warranty
Returns & Satisfaction Guarantee
We stand firmly behind the quality of every product we sell. Your confidence matters to us — and we back it with a straightforward 30-Day Satisfaction Guarantee.
If you are not fully satisfied, you may request a return within 30 days of delivery. All returns must receive pre-approval prior to being sent back. Unauthorized returns will not be accepted.
To qualify for a return:
Item must be in new, unused condition
Product must be in its original packaging
All parts, components, hardware, manuals, and accessories must be included
Packaging must be undamaged and suitable for resale
Important:
Electronics are strictly inspected. No returns on open-box electronics. Exceptions may apply only with prior written approval. Any electronic unit that has been installed, powered, activated, or altered may not be eligible for return.
We are serious about product integrity — and equally serious about taking care of our customers. If there is ever a product issue, contact us immediately so we can make it right.
For return authorization, please contact our support team before shipping anything back.